Stability of halides decreases down the group since the size increases and charge density decreases, which leads to stability and we get the order of stability as follows:

$$\ce{F-} < \ce{Cl-} < \ce{Br-} < \ce{I-}$$

But while referring to a textbook, I found that the stability of halides of group 17 decreases from top to bottom:

$$\ce{F-} > \ce{Cl-} > \ce{Br-} > \ce{I-}$$

Where did I go wrong?

  • $\begingroup$ If you do not even try to find an answer yourself, do not expect help of others. Trying is more important than avoiding wrong ideas. $\endgroup$
    – Poutnik
    Nov 26 '21 at 5:25
  • $\begingroup$ Following the recommendation in the comment above is even quite easy, at least if the order is all you are looking for. $\endgroup$
    – Alchimista
    Nov 26 '21 at 12:12
  • 1
    $\begingroup$ By halides of group 17, are there meant interhalogen compounds, or was the original 16 correct? $\endgroup$
    – Poutnik
    Nov 26 '21 at 19:25

Stability with respect to what? Any halogen taken by itself is perfectly stable so you must define a reaction or interaction to compare the different elements. Your question has nothing to do with the chemistry of the halogens. You went wrong in not reading your sources with care and not thinking through the chemistry.


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